MiniStack 1.4.0 ships four new services that emulate Amazon Bedrock end to end, and one env var that turns the mock into a real LLM backend.
The default: deterministic, shape-perfect mocks
Out of the box, Converse and InvokeModel return deterministic mock responses whose wire shape matches the model family you asked for. Anthropic, Titan, Nova, Llama, Mistral, Cohere and AI21 each have distinct response schemas, and MiniStack selects the right one by model ID prefix. Streaming operations (ConverseStream, InvokeModelWithResponseStream) use the real eventstream wire format, so your SDK's streaming parser runs exactly as against AWS.
That means your test suite exercises the real code paths: request building, response parsing, stream handling. No network call, no API bill.
One honest caveat: token counts are a chars/4 heuristic. Shape-correct, but don't assert exact values against a mock.
